Caster of the disappearing type



March 17, 1953 D, MGKEAN 2,531,329

CASTER OF THE DISAPPEARING TYPE Filed Aug. 26, 1950 JAMES D. MG KEAN Gttornegs Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE CASTER F THE DISAPPEARING TYPE JamesD. McKean, Seattle, Wash.

Application August 26, 1950, Serial No. 181,595v

4 Claims.

My invention concernsV a caster for an article of furniture or the like; and, more particularly, is a caster of the disappearing type. Briefly, the caster includes an upright cylindrical guideway to be positioned within the leg of the article to be supported; a circular traveller vertically reciprocal in the guideway between a lower and an upper. position; an operating shaft running through the upper portion of the guideway; a toggle secured to the operating shaft and the traveller to raise and lowerA the traveller and lock it in its lower position; a circular turntable secured to the traveller in a manner permitting rotation of the same about a vertical axis; and a pair of fork arms having a wheel secured at one end and pivotally secured at the other end to the turntable, to swing about a horizontal axis, the latter ends of the fork arms being V-shaped to form stop limits for swinging movement of the fork arms.

lt has long been recognized that it is desirable to have a caster of the disappearing type for furniture and like articles which are most easily moved on casters but which appear best and. are most stable when the legs support the article directly by resting on the iioor. Various attempts have been made to construct a desirable caster of this type. Some of these casters have `been well designed for particular uses, but the present caster has many virtues over casters adapted for analogous uses. A principal problem in casters which retract into the leg of an article is caused by the fact that the caster, to properly function, must have the supporting arm of the wheel extend at an angle to the longitudinal axis of the leg with the wheel positioned at one side of that longitudinal axis. When the caster is drawn up in the furniture leg, the sup-porting varrn and wheel must somehow be accommodated. A common solution is to make the leg large enough so that the arm and wheel may remain in the same relative position in regard to the longitudinal axis of the leg. Such a bulky leg is most objectionable in many types of articles.

A common problem in all casters is to provide a firm support for the supporting arm of the caster wheel while providing for swivelling rotation of the arm about a vertical axis. This problem has been attempted of solution in different ways with varying degrees of success. It is desirable that the support provide for rotation with a minimum of friction so that the wheels will swivel with ease in moving the furniture as well as for avoiding damage to the caster.

The objects ofmy invention include: providing a caster of the disappearing type in which the supporting arm for the wheel assumes a vertical position upon withdrawal whereby the furniture leg may have a minimum of bulk; designing a workable caster with a disappearing wheel of a large size; providing a caster of the disappearing type of improved construction for appearance, strength and workability and which is economical to manufacture; designing a caster with a rm support forl the wheel and supporting arm while at the same time providing for rotation of the same with a minimum of friction; and to furnish a caster of the disappearing type with simple, eiicient means of lowering and raising the wheel and rmly securing the wheel in its lower position.

My invention will best `be understood from the following description when read with reference to the drawings, in which:

Figure 1 is an elevational view, partly in seotion, of a specic embodiment of my invention, in which the caster wheel is in an upper position;

Figure 2 is an elevational view, partly in section, similar to Figure l except that the cutting plane is at right angles to the cutting plane in Figure 1 and the caster wheel is in a lower position; and

Figure 3 is an exploded view, on an enlarged scale, of the turntable, fork arms, Wheel and associated parts.

The guideway lo of my caster is preferably formed as an upright tube which, while shown cylindrical, may be of any suitable cross-section. Disposed to reciprocate in guideway l0 are traveller l2, turntable l, a pair of fork arms I6, and wheel IS.

The reciprocating parts are activated by operating shaft 2B, acting through a toggle formed oy an upper toggle link 22 and a lower toggle link 2li.

Guideway l may be of square or round crosssection. Guideway lil may be positioned in the leg of a piecev of furniture or the like, the installation'being simple as only a longitudinal cylindrical bore is made to accommodate guideway H3 when the guideway is in the form of a cylinder. A transverse circular bore is made for operating shaft 2i). The of the furniture does not have to be changed from symmetrical design to accominodate the caster. The lower edge of guideway it would be positioned near the lower end of the articleleg which conceals the caster. Only one end of operating shaft 29, as at 3o, has t-o extend outside of the furniture leg. In this way, an

easily installed construction is provided which' does not'detract from the appearance of the sup- Y 5 ported article. Y Y

The extending end of" operating shaft 2) is squared, as at 30, or otherwise formed to accommodate a wrench or handle for operating the same. Upper toggle link 22 is flxedly secured to operating shaft 20 by means of a key 2 I, and joins with lower toggle link 24 as by bolt 32 and cotter pin 34. Lower toggle link 24 has preferably a pair of arms, positioned on either side of upper toggle link 22 and boss 36 on traveller I2. The arms of lower toggle link 24 are pivotally connected to boss 36 Yby bolt 38 and cotter pin 4l). Operating shaft 20 is positioned at one side of the longitudinal axis of cylindrical guideway Ill. As will be noted from Figure 2, lower toggle link 24 has a bend at 42 and connects at the center of traveller I2. With this positioning of the operating shaft, shape of the toggle links and point of connection with the traveller, the locking action shown in Figure 2 is obtained.V The toggle abuts the wall of the guideway below operating shaft 20 in the locked position; and shaft.

20, bolt 32, and bolt i9 must pass an aligned position in moving traveller I2 from a lower to an upper position. This construction provides rrn locking of traveller i2 in its lower position and easy movement of traveller i2 from lower to upper position and back.

Turntable I4 is secured I'below traveller i2 by means permitting rotation of turntable I d about a vertical axis. The means of securing shown in Figure l is screw E@ running through opening 52 in turntable I and threaded into traveller I2. Ball bearings 54 are positioned between turntable I4 and traveller I2 in circular races. The ball bearings provide for easy rotation of wheel I8 and arms I6 about a vertical axis; while, at the same time, wheel i8 is held stably in regard to shifting of its support. These are quite important factors as wheel i3 and arms i@ must be able to shift quickly as the article supported is moved in various directions and even if the 'article is quite heavy. One of the most frequent failures in casters is due to insuflicient securing of the assembly about which the wheel arms rotate. With the circular turntable, reciprocal traveller, solid and rigid guideway, operating shaft, toggle and associated structure, turntable Iditurns easily and maintains its horizontal positioning thereby forming a stable support for fork arms I6 and wheel I8.

The construction of wheel I8, fork arms l, and turntable I4, provides for retraction of wheel i8 in a position below turntable l, an important feature of my invention. It will be noted that the diameter of wheel I8 is quite large in comparison with the diameter of guideway I0, which is possible with such positioning of wheel IS in retracted position. type lack this feature and either the guideway must be oversized in comparison with the desirable size for most furniture or other uses, or the Wheel must be of small size, or the wheel must extend to the side of the guideway in its upper position.

v Turntable iii has two parallel slots 6@ spaced equally on either side of opening 52. The upper' ends of fork arms I6 are pivotally secured in slots ti) by pins 62 running through openings ed in turntable I 4 and openings 66 in fork arms I d. The lower ends of fork arms I6 are pivotally secured to wheel I8 by bolt 58 and nut 'IS running through openings 'I2 in fork arms I6 and central opening 'i4 in wheel I8. Y

Limits on the swinging of fork arms i are provided by the abutting of portions of fork arms I6 against `the bottom of slots 60. The abutting Previous casters of the disappearing portions of fork arms I6, as at d, are formed by beveling the ends of fork arms IS on either side of the center. In supporting position, the coaction of the fork arms and turntable I4 forms a secure support for wheel I3 positioned to the side of the longitudinal axis of guideway IB. Upon movement of traveller I2 upwards, fork arms i6 assume a vertical position and Wheel I8 is centered with guideway Iii.

While I have described a specific embodiment of my invention, various modications will be apparent to those skilled in the art and I wish to be understood as claiming all modications within the scope of my invention.

I claim:

l. In a caster of the disappearing type, the combination, comprising: an upright cylindrical guideway to be positioned or included within the leg of the article to be supported; a circular traveller vertically reciprocal in said guideway between a lower and an upper position; an operating shaft running through the upper portion of said guideway and to one side of the center thereof; a toggle formed by an upper and a lower toggle link joined together with the free end of the upper link iixe-dly secured to said operating shaft and the free end of the lower link pivotally connected to said traveller, said traveller being locked in said lower position by the abutment of said toggle against the wall of said guideway beneath said operating shaft in extended position, said toggle links passing an aligned position when activated by said operating shaft to move said traveller from said lower to said upper position; a circular turntable; means of securing said traveller and said turntable together at their centers permitting rotation of said turntable about a vertical axis; ball bearings between said traveller and said turntable, said traveller and said turntable having circular races in their opposed faces in which said ball bearings are positioned; a wheel; a pair of fork arms secured at one end to said wheel; said turntable having two parallel slots spaced an equal distance from the center of said turntable on either side thereof; the other end of said pair of fork arms being pivotally secured in said slots, said fork arms being so shaped as to abut the Ibottom of said slots when the fork arms are disposed at a predetermined angle to said turntable, thereby forming limits on the swinging movement of said fork arms.

2. In a caster of fthe disappearing type, 4the combination, comprising: an upright cylindrical guideway adapted to be positioned within the leg of the articleV to be supported; a circular traveller vertically reciprocal Iin said guideway between a lower land an upper position; an operating shaft running through the upper portion of said guideway; a toggle mechanism having a rst link which is xedlysecured at one end to said operating shaft and having a second link which is pivotally connected at one end to said traveller and at the other end to the other end of said first link, said traveller being locked in said lower position by the abutment of .said toggle against the wall of said guideway, said operating shaft being rotatable to moveV said toggle from abutment with said wall for unlocking said traveller and for moving said traveller to said upper position; a circular `turntable secured to said traveller in a manner permitting rotation of said turntable about a vertical axis; a wheel; a Vpair of fork arms secured at one end to 'said wheel and pivotally secured at the other end to saidturntable at the center thereof to swing about a horizontal axis; said fork arms and said turntable having abutting surfaces providing stop limits lfor swinging movement of said fork larms about said horizontal axis and said wheel having a diameter almost as large as the diameter of the inner -wall-s of said guideway.

3. In a caster of the disappearing type, the combination, comprising: an upright cylindrical guideway lto be positioned or included within the leg of the article to be supported; a ycircular traveller vertically reciprocal in said guideway between a lower and an upper position; a circular turntable; means securing said traveller and said turntable together at their lcenters permitting rotation :of said turntable about -a vertical axis; ball bearings between said traveller and said turntable, said traveller and said turntable having circular races in their opposed `faces in which said ball bearings are positioned; a wheel; a pair of fork arms secured at vone end to said wheel; said turntable having two parallel slots spaced an equal distance from the center of said turntable on either side thereof; the other end of said pair of fork arms being pivotally secured in said slot, said fork arms being so shaped as to abut the bottom of said slots when said fork arms are disposed at a predetermined angle to said turntable, thereby forming limits on the swinging movement of said fork arms; and means for locking said traveller in said lower position.

4. In a caster of the disappearing type, the combination, comprising: an upright cylindrical guideway adapted to be positioned within the leg of the article to be supported; a circular traveller vertically reciprocal in said guideway between a lower and an upper position; an operating shaft running transversely through the upper portion of said guideway; a toggle mechanism having a rst link which is xedly secured at one end to said operating shaft and having a second link which is pivotally connected at one end to said traveller and at the other end to the other end of said rst link, said traveller being locked invsaid lower position by the abutment of said toggle against the wall of said guideway, said operating shaft being rotatable to move said toggle from abutment with said wall for unlocking said traveller and for moving said traveller to said upper position; a turntable secured to said traveller in a manner permitting rotation of said turntable about a vertical axis; a wheel; and a supporting member for said wheel secured to said turntable at one end and rotatably supporting said wheel at the other end.

JAMES D. MCKEAN.

REFERENCES CITED The following references are of record in the le of this Ipatent:

UNITED STATES PATENTS Number Name Date 30,505 Stafford OOt. 23, 1860 952,694 Ward Mar. 22, 1910 987,064 Grotenhuis Mar. 14, 1911 1,016,745 Henrikson Feb. `6, 1912 1,022,646 Toll Apr. 9, 1912 

